In the coordination compound [Pt(NH3)2Cl2], the coordination number and oxidation number of the central atom a

Question

In the coordination compound [Pt(NH3)2Cl2], the coordination number and oxidation number of the central atom are, respectively,
a. 2, 0.
b. 4, +4.
c. 5, 0.
d. 4, +2.
e. 6, +2.

Answer 1

d. There are four things attached to the Pt ion. Since NH3 is neutral, Cl- has a negative charge, but the compound is neutral, the Pt ion must have a +2 charge.

Answer 2

e 6 +2

Answer 3

The answer is d. Pt is coordinated to 2 NH3 and 2 Cl molecules. Since Chloride has a -1 charge and there are two of them, the Pt must have a +2 charge for the molecule to be neutral.

Answer 4

The answer is d. As explained above, the presence of the chloride ions indicate that this is Pt(II), which makes platinum d8. While metals with other electron counts usually prefer being 6-coordinate, d8 metal ions [Ir(I), Pt(II), Pd(II), Rh(I), etc.] often go four-coordinate due to orbital reorganization. This minimizes the energy of all the occupied orbitals (with 8 d electrons, four of the five d orbitals will be occupied) by minimizing the energy of all orbitals having a z component. Anyway, that's a molecular orbital theory explanation for why this is not a six-coordinate complex. Assuming there must be two ligands present that aren't shown and guessing six-coordinate is understandable though, since that is by FAR the most common coordination number for transition metal complexes in general.